The number of students attending "High-Poverty and mostly Black or Hispanic" (H/PBH) public schools — including charter and magnet schools — more than doubled between 2001 and 2014.

Charter schools are publicly funded but privately run while magnet schools have specialized curricula.

Students in H/PBH schools increased by 4.3 million during that time, from about 4.1 million to 8.4 million.

It's disheartening news, especially considering that the US Supreme Court ruled in Brown v. Board of Education of Topeka in 1954 that school segregation was unconstitutional.

Many districts across the nation have acknowledged the issue while attempting to remedy the racial stratification in their schools. GAO highlighted in their report three such districts that implemented actions to increase racial and socioeconomic diversity in schools.

Each of the districts, identified only by geographic location (Northeast, South, and West), experienced challenges in reducing segregation in their schools.

The district they profiled in the South, for example, changed existing school-assignment zones in an effort to fix the problem. The new attendance zones allowed more choice for parents to decide where to send their children.

Segregation in the district got worse, however, in part because the district couldn't control the choices parents made on schooling. The district also said that some families chose to send their children to private schools and that they believed that some white families did not want to send their students to more diverse schools.

The school district was investigated by the Department of Education and served with a federal lawsuit.

The current-day battle over segregation is playing out in real time in school districts across the nation.

On Monday, a federal court ordered middle and high schools in Cleveland, Mississippi, to merge to satisfy the ruling on a decades-long legal battle to desegregate schools, according to a press release from the Department of Justice.